Justice Cromwell’s retirement therefore frees up that solitary Atlantic Canada seat, meaning that his replacement will almost certainly hail from either New Brunswick, Nova Scotia, Prince Edward Island (“PEI”), or Newfoundland and Labrador (“NL”). To date, five judges were selected from Nova Scotia, six from New Brunswick, and only one from PEI.

Since John A. Macdonald named Sir William Johnstone Ritchie for Atlantic Canada, there has been someone representing the region at the High Court. Such arrangement has become integral to the composition of the Court.

The established convention is not a statement of preference in the way that one prefers chocolate ice cream instead of vanilla. The convention exists to ensure that key federal institutions like the High Court have a balance of voices and do not exclude any region of the federation.

Even though the Supreme Court of Canada is governed by statute (The Supreme Court Act, 1875), the Constitution Act, 1982 spells out in one of its amending formulae (Section 41) that the “composition of the Supreme Court of Canada” requires the unanimous consent of the Parliament of Canada (The House of Commons, the Senate and the Crown) and all 10 Provincial Legislatures.

Removing Atlantic Canadian representation from the Court alters its “composition,” which from a constitutional perspective calls into question the unilateral prime ministerial announcement.